Zyvox, Methylene Blue Interact with Some Psych Meds

The U.S. Food and Drug Administration (FDA) has announced an update to information on the potential drug interaction between Zyvox (linezolid) and serotonergic psychiatric medications. The FDA is also issuing another Drug Safety Communication (DSC) for methylene blue for similar potential drug interactions with serotonergic psychiatric medications.

Not all serotonergic psychiatric drugs have an equal capacity to cause serotonin syndrome with Zyvox, notes the FDA.

Most cases of serotonin syndrome with Zyvox reported to the FDA’s Adverse Event Reporting System (AERS) took place in those patients taking specific serotonergic psychiatric drugs, namely a selective serotonin reuptake inhibitor (SSRI) or a serotonin norepinephrine reuptake inhibitor (SNRI). The FDA noted that it remains unclear if Zyvox administration in patients receiving other psychiatric drugs with lesser degrees of serotonergic activity poses a similar risk; the agency pointed out that it will update the public when new information becomes available.

According to the FDA, it has received reports of serious central nervous system (CNS) reactions when the antibacterial drug, Zyvox, is given to patients taking psychiatric medications that work through the serotonin system of the brain, so-called serotonergic psychiatric medications. A list of serotonergic psychiatric medications that can interact with Zyvox can be found in the FDAâ€™s Drug Safety Communication at: http://www.fda.gov/Drugs/DrugSafety/ucm265305.htm.

According to the agency, safety information about this potential drug interaction, as well as critical drug usage recommendations for emergency and nonemergency situations, are being added to drug labels for serotonergic psychiatric medications and Zyvox. The methylene blue DSC that was just released also includes drug usage recommendations.

Zyvox, which is a reversible monoamine oxidase inhibitor (MAOI), is used in the treatment of infections such as pneumonia, infections of the skin, and infections caused by a resistant bacterium including Enterococcus faecium. While the exact mechanism of this drug interaction is unknown, it is known that Zyvox inhibits the action of monoamine oxidase A, an enzyme responsible for breaking down serotonin in the brain.

It is believed that when Zyvox is given to patients taking a serotonergic psychiatric medication, high levels of serotonin can build up in the brain. This can cause a toxicity known as Serotonin Syndrome, which can lead to mental changes, such as confusion, hyperactivity, and memory problems; muscle twitching; excessive sweating; shivering or shaking; diarrhea; trouble with coordination; and/or fever.

The FDA strongly recommends that Zyvox not be given to patients taking serotonergic drugs; however, the agency notes that some conditions may be life-threatening or require urgent treatment with Zyvox, such as in the treatment of vancomycin-resistant Enterococcus faecium (VRE) infections or nosocomial pneumonia and complicated skin and skin structure infections, including those caused by methicillin-resistant Staphylococcus aureus (MRSA).

Patients should not stop taking their serotonergic psychiatric medicine without first talking to a healthcare professional.